Counterbalanced door for cargo carrying vehicle bodies



March 26, 1957 T. c. wHrnNG 2,786,712

COUNTERBALANCED DOOR FOB CARGO CARRYING VEHICLE BODIES Filed NOV. 29,1954 Ii Fglfu q Q CUN'EERBALANCED DR FOR CARGO CARRYNG VEHICLE BODIESTheo C. Whiting, Akron, N. i?.

Application November 29, 1954, :Serial No. 471,786

3 Claims. (Cl. 296-106) This invention relates to counterbalanced,vertically movable doors for cargo carrying trucks and trailers wherethe door is guided by a pair of side tracks, each having a verticalsection alongside the doorway and connecting with a horizontal sectiondisposed under the ceiling of the truck or trailer ybody through acurvedpart,

One of the principal objects of the present invention is to provide sucha counterbalancing device which is wholly housed within the body of theAtruck .or trailer but at the same time does not occupy any space thatcould otherwise be occupied by the payload.

Another object is to provide such a counterbalancing device which isinconspicuous and at the same time will adequately counterbalance theweight of the door.

Another object is to provide such a counterbalancing device, the eilectof which is proportional to the increasing effective weight of the dooras it descends.

Another object is to provide such a counterbalancing device which canhave an adjustable amount of windup thereby to adapt it to doors ofdifferent sizes.

Another object is to provide such a counterbalancing device, the partsof which are adequately protected against accidental injury, as from ashift of the cargo.

Another aim is to provide such a counterbalancing device which isextremely inexpensive in construction and operation and which will standup under conditions of severe and constant use without getting out oforder or requiring repairs.

Another object is to provide such a counter-balancing device having alatch which is yieldingly held closed by tension members of the device.

Other objects and advantages of the invention will be apparent from thefollowing description and drawings in which:

Fig. l is a vertical, longitudinal section through the rear end of atruck body having a rear door counterbalanced in accordance with thepresent invention, the forepart of the truck body and its chassis beingshown in phantom.

Fig. 2 is an enlarged, lfragmentary, yvertical section taken generallyon line 2 2, Pig. l.

Figs. 3 and 4 are fragmentary cross sections taken generally on thecorresponding lines of Fig. 2.

Fig. 5 is a fragmentary rear elevational view of the truck body and itsclosed door, viewed from the lower left of Fig. 3.

Figs. 6 and 7 are fragmentary, horizontal sections taken on thecorrespondingly numbered lines of Fig. 5.

The numeral iti represents the-body of a tnuck 11, this body having theusual floor or platform 12, side walls 13 and roof i4, the rear end ofwhich roof is shown as extending downwardly, as indicated at 15, toprovide the upper limit fof the doorway 16 at the rear of the truck bodyand which doorway extends from lthe floor to the bottom edge of the.downward extension i5 .and from one side -Wall 13 to the other. Thecargo is loaded into the truck body and 4removed therefrom through thisdoorway.

2,786,712 Patented Mar. 26, 19.57

ice

ln transit, the doorway 16 s closed by a vertically movable door it?which is shown as made of three rectangular sections hinged together andcomprising a top section, an intermediate section and a bottom section.At their four corners, these sections are each provided withconventional rollers 2i? which project into channelshaped, parallel sidetracks 21 mounted on the side walls t3 o the truck. Each of these tracks21 includes a vertical part 22 extending along the corresponding side ofthe opening 16, a horizontal part 23 arranged immediately under the roof14 and a curved portion 24 which connects the portions 22 and 23 of eachrail vand guides the rollers 2d so Athat the several sections 19 of thedoor follow the track when raised from the vertical closed positionshown in Fig. l and so that in the open position of the door, theseveral sections thereof' are arranged horizontally immediately underthe roof 14 and supported by the horizontal parts 23 of the tracks.

It will particularly be noted that with above conventional constructionof truck body, track and door, there is a space Za' which cannot beoccupied by any part of the cargo or payload of the truck and whichspace also is not traversed by the door 18. This space is defined by therear end of the roof 1d, its downward extension 15, and the curved part24 of the two tracks 21. This space 2S cannot be occupied by the' cargosince otherwise the door 18 could not be opened and closed. Also thisspace cannot be traversed by the door because a curved track section 24of substantial extent is required to eiiect transition of the door fromthe horizontal parts Z3 to the vertical parts 22 of the tracks 21 andvice versa. ln the practice of the present invention, this space 25 isutilized to house the counterbalancing device forming the subject of thepresent invention.

As best shown in Fig. 2, the counterbalancing device includes a centralrod in the form of a tube 3i) which `is supported by L-shaped bracketsor hangers 31 and 32 so as ,to be parallel with and in closely spacedrelation to the roof i4 and its downward extension 15. A`ccordingly,this rod 3d occupies the space 2S and it is supported by extendingthrough openings provided in the brackets or hangers 3T. and 32 andwhich brackets or hangers are shown as secured by screws 33 to the roofkof the truck body. This rod is held stationary and for this purpose hasa pair of cotter pins 34 extending diametrically therethrough onopposite sides of the hanger or bracket 32, as best shown in Figs. 2 and4. The heads `of these cotter pins are secured to the hanger or bracket32 by a bolt 35 and since these cot'ter pins 34 are bolted to the hangeror bracket 32 and extend through the rod 3d, it will be seen that theseCotter pins prevent rotation of the rod 3d as well as endwise movementof the rod.

lt is important, as hereinafter described, to adjust the degree ofpretensioning or windup of the counterbalancing device and to this endthe rod 3l) is capable of being fixed in different positions ofrotation. When adjusting of the degree of windup is required, the bolt35 is removed and a pair of bars or pins 36 are inserted through twopairs of holes 3S in the opposite end of the rod 30. By manipulation ofthe bars 36, the rod 36 can be rotated any desired number of times inthe required direction following which the bolt '35 vcan be replaced toextend through the 'heads of the cotter pins 34 and the hanger orbracket 32.

The rod 30 is vsurrounded by a helical spring '40, one end 41 of whichis arranged adjacent the bracket or hanger 32 while the other end 42 ofthis spring is ar ranged adjacent the bracket or hanger 31. The end 41exten-ds through an opening in the annular flange 43 of :a Ycollar 44,the hub kof which is welded to the rod 30 .as indicated at 45. Theopposite end 42 .of the spring 40 extends through an opening in an`annular flange or collar 46 which is welded to a ring 48, the latterbeing in turn welded, as indicated at 49 in the bore of a tube or drumt). This tube or drum 5d is journalled on the perimeter of the flange 43welded to the stationary rod and its flange or collar 46 is journalledon the opposite end of this stationary rod 39. A small thrust collar 51is Welded on the rod 30 and engages the inner face of the collar 46 andacts as a thrust shoulder to resist the thrust produced by the action ofthe spring d?.

The outer tube 50 forms a drum on which a counterbalancing cable windsand unwinds as the door is opened and closed. One end 56 of this cableextends through the outer tube or drum Sil and is anchored in the collar46. The other end of this cable extends downwardly through the space 5Sbetween the door 1S and the ldownward extension 15 of the roof 14 and issecured at its lower end to the bottom of the door as follows:

The numeral 6ft represents a metal plate secured by screws 61 to theouter face of the lowest section 19 of the door 1S near the bottomthereof. rlhis plate has an upper ange 62 which is centrally indented toreceive the cable 55 as best shown in Figs. 5 and 6. This plate also hasa lower flange 64 in which the end of the cable 55 is anchored by anysuitable connector 65. This plate -also has welded thereon a vertical,cylindrical tube 66 in which the vertical rod d is journalled, thisvertical rod also extending through an opening in the lower flange 64 ofthe plate. The rod 63 is bent at right angles -at its upper end toprovide an operating handle 70 and is bent at its lower end at rightangles to provide a latch 71. The latch 71 extends at right angles tothe handle 70 and when the handle 7@ is arranged against the rear faceof the door 18, the latch 71 is engaged under a catch 72, the base 73 ofwhich catch is secured to the end of the floor 12 of the truck.

A feature of the invention is that the cable 55 bears against the handle70 so as to yieldingly hold it against the plate 60, in which position,when the door 1S is closed, the latch 71 is engaged with the catch 72.The plate B can also be provided with a projection '74 and thisprojection can be provided with a hole lalining with a hole 75 providedin the upper flange 62 of the plate 60. These holes are adapted toreceive a conventional freight car door seal (not shown), the removal ofor tampering wit-h which indicates that unauthorized persons have beenattempting to get at the sealed cargo.

In the operation of the counterbalanced door forming the subject of theinvention, assuming the door 18 to be in the closed position shown inFig. l, the driver under the catch 72 so that by lifting upon the handle70, the door 18 is Istarted in its upward movement. As soon as hereleases the handle 70, the tension of the cable 55 draws it backagainst its supporting plate 6i) and where it cannot injure anyone inthe continued upward, or return downward, movement of the door 1%.

The driver then seizes the lower end of the door 18 and lifts the door,the rollers 2i) of the successive door sections 19 traveling around thecurved parts 24 of the side tracks 21 and onto the horizontal parts 23of these side tracks. In the latter position, the doorway 16 is fullyopened and the cargo can be removed from the truck body.

The lifting of the door 18 is facilitated by the lifting device attachedto the cable 55. This `cable is arranged against the outer face of thedoor 18 in the closed position thereof and extends upwardly through thecrack or space 58 to the drum Si) on which the cable winds. This drum isjournalled on the periphery of the flange 43 at one end of thestationary rod 30 and its collar 46 is journalled on the opposite end ofthe stationary rod 30. Since the helical windup spring 40 is anchored atits opposite ends in this flange 43 xed to the rod 3ft and the collar 46Xed to the drum 5G, and since this spring has been provided with therequisite degree of windup, the spring exerts a counterbalancing forceon the closed door 18, tending to rotate the drum Si) in the directionto wind the cable 55 upon this drum. As the door rises and as a greaterpart of this door is supported on the horizontal section 23, the forceof the windup spring 40 diminishes. Accordingly, the eifect of thespring is diminished with the reduction in the load which itcounterbalances.

After the cargo is removed and the truck body reloaded, the operatorseizes the rear end of the ydoor 18 and pulls it downwardly, thereby tocause the several sections 1? thereof to traverse the curved parts 24 ofthe side tracks 21 and enter the vertical parts 22 thereof. As theseveral sections of the door 18 move downwardly along the vertical parts22 of the side tracks, the door draws upon the cable 55 `causing it toturn the drum Si) and thereby rewind the helical spring di). When thedoor approaches its fully closed position, the driver pulls the handletoward him thereby displacing the cable 55 toward hi-m against theresistance of the tension of this cable. In this position of the handle7l), the catch of the latch 71 at the lower end of its vertical rod 68is in position to clear the catch '72. Accordingly, the door can befully closed following which the driver releases the handle 70. When soreleased, the tension of the displaced cable 55 draws the handle 7)against the plate 60 and also swings the latch 71 under the catch 72.Accordingly, the cable 5S yieldingly holds the door rmly latched untildeliberately released by the driver in pulling the handle 70 toward him.

`if required, the cargo can be sealed by passing a conventional car doorseal 4through the apertured lug 74 and hole 75, this preventing thehandle 7G from being drawn forwardly without breaking the seal.

. lf a greater degree of counterbalancing is required, a pair of bars orpins 36 can be placed in the two pairs of holes 3S and the bol-t 35 canbe withdrawn. By Inanipulation of the two pins or bars 36, the centralrod 39 can be rotated to the position to provide the necessary degree ofpretensioning or windup of the spring dit. Thereafter, the bolt 35 canbe replaced.

`From the foregoing, it will be seen that the present invention providesa very simple and `etfective counterbalance for the vertical movingdoors of trucks and which in particular is characterized by thecounterbalancing spring mechanism being arranged in the space 25 whichspace cannot be occupied by the cargo and also cannot be in the path ofthe door. Accordingly, the usable volume of truck or trailer body is notreduced in the practice of the present invention. It will further beseen that by arranging the cable on the outside of the door, it does notinterfere with the movement of the door to its open horizontal positionand at the same time, the cable is utilized to hold the door latched.

l claim:

l. In a cargo carrying vehicle body having a loor, side walls and a roofhaving a rear downwardly extending portion deining with said side wallsand floor a doorway, a pair of parallel tracks severally arranged ateach side of said body and each track including a vertical part arrangedalongside of said doorway, a horizontal part under said roof andextending along the corresponding side wall and a curved part connectingeach vertical part with its horizontal part and a door having rollersriding and guided by said tracks and said door being movable fromaclosed vertical position in said vertical parts of said tracks upwardlyand around said curved parts to said horizontal vparts of said trackswhere said door is in a horizontal position; the combination therewithof means for counterbalancing said door in its movement along saidtracks and latching said door in its closed position, comprising agenerally horizontal rod fixed to said body generally parallel with saiddownwardly extending portion of said roof and arranged in the spacedefined by said roof, said downwardly extending part of said roof andsaid curved parts of said tracks, a drum iournalled on said rod, ahelical spring within said drum around said rod and having one end fastto said rod and its other end fast to said drum and a cable wound aroundsaid drum and having one end fast to said drum, the other end of saidcable extending downwardly through the space between said downwardlyextending part of said roof and said door and along the exterior face ofthe door when closed, means fastening said other end of said cable tothe lower part of said door a catch fast to the exterior of said bodyadjacent said cable, a latch movably mounted on said door for movementinto and out of engagement with said catch in the closed position ofsaid door, a swingable handle arranged between said cable and door, andmeans operatively connecting said latch and handle and operative to holdsaid latch engaged with said catch when said handle is held by saidcable against said door.

2. The combination set forth in claim l wherein said means operativelyconnecting said latch and handle comprises a vertical tube fast to saiddoor and a vertical rod journalled in said tube with said handle formedas a horizontal extension of the upper end of said rod and said latch asa horizontal extension of the lower end of said rod.

3. In a cargo carrying vehicle body having a floor, side walls and aroof having a rear downwardly extending portion defining with said sidewalls and oor a doorway, a pair of parallel tracks severally arranged ateach side of said body and each track including a vertical part arrangedalongside of said doorway, a horizontal part under said roof andextending along the corresponding side wall and a curved part connectingeach vertical part with its horizontal part and a door having rollersriding and guided by said tracks and said door being movable from aclosed vertical position in said vertical parts of said tracks upwardlyand around said curved parts to said horizontal parts of said trackswhere said door is in a horizontal position; the combination therewithof means for counterbalancing said door in its movement along saidtracks, comprising a generally horizontal rod fixed at its opposite endsto said body adjacent said side walls to extend generally parallel withsaid downwardly extending portion of said roof and to be arranged in thespace defined by said roof, said downwardly extending part of said roofand said curved parts of said tracks, a cy1indrical drum journalled atits opposite ends on the opposite extremities of said rod, a helicalspring within said cylindrical drum around said rod and having one endfast to said rod and its other end fast to said cylindrical drum and acable having successive convolutions wound around the periphery of saidcylindrical drum to have a helical lead -extending lengthwise of thedrum and having one end fast to one end of said drum, the other end ofsaid cable extending downwardly through the space between saiddownwardly extending part of said roof and said door and into and alongsaid doorway along the exterior face of the door when closed and meansfastening said other end of said cable to the lower part of said door,whereby the upper end of said cable can travel any required distancelengthwise of said drum as said door is opened and closed thereby toprevent jamming of said cable between said downwardly extending part ofsaid roof and said door.

References Cited in the tile of this patent UNITED STATES PATENTS

